Whoever fitted out my little boat had serious worries about going overboard. She has 4 of these clipping on points,2 on the foredeck(which jackstays can be fitted to ) and 2 in the cockpit.The bar is 12 mm stainless rod ,each plate is held on with no fewer than 8, 8mm bolts with stainless backing pads and washers.
Puts a lot of much bigger boats to shame in this department.
I have to admit though the number one use is as somewhere to hang the sail ties...
They are used (and sold) as pontoon rings over here, found just about everywhere for fast clipping-on of mooring warps with carabiners attached. Really quick when you are single-handed and mooring bows-on!
Possibly a major reason for this particular kind of fitting was cost! Works out about 15-20€/station but clearly not the best grade of stainless...
Nice idea though, if you mind mind a slightly "agricultural but functional" look (meant in a nice way!).
"Would'nt lifelines running the length of the deck give more flexibility for clipping on?"
Simple answer is yes, the ones on the foredeck can be used to secure the forward ends. In practice though I rarely have to go forward (thanks to the roller furling genoa )and can clip to the base of the mast go forward then transfer the clip to the points on the foredeck if needed.
I wondered what they were originally designed for.I can live with the agricultural look safe in the knowledge that they would hold Pavarotti trailing on his harness sling in a force 10!
Having attended the funeral of a friend who was towed in his harness alongside his boat I now fit jackstays on the coachroof and terminate them far enough inboard so that the harness line will pull tight as I make contact with the guard rails or pulpit. A jackstay or attachment fitting that allows you to go over the side is leaving it far too late, especially if single handed.
My late friend was a yachtmaster instructor and master mariner but still made a fatal error.